/*TITLE supermarket pricing include file */

/****keyword-flag*** "%v %f %n" */
/* "11 20-Mar-98,20:29:58 SUPERM.H" */

#include <string.h>
#include <minmax.h>
#include "radix40.h"
#include "bcdconv.h"

const int DESCRIPTION_WORDS = 7;
const int DESCRIPTION_CHARS = (CPW*DESCRIPTION_WORDS);

const int FILE_CAPACITY = 1000;
const unsigned FILE_SIZE = ((unsigned)(FILE_CAPACITY*1.25));
const int BCD_KEY_SIZE = 5;
const int ASCII_KEY_SIZE = (BCD_KEY_SIZE*2);

const unsigned char INVALID_BCD_VALUE = 0xFF;
const unsigned char DELETED_BCD_VALUE = 0xFE;

const unsigned INVALID_RECORD_NUMBER = 0xFFFF;

const int MAPPING_FACTOR = 8;  /* how many slots can be used by any one record */

const double CACHE_FACTOR = .20;

const int APPROXIMATE_CACHE_SIZE =
  (max(int(FILE_CAPACITY*CACHE_FACTOR),MAPPING_FACTOR));

const unsigned CACHE_SIZE =
  ((unsigned)(APPROXIMATE_CACHE_SIZE/MAPPING_FACTOR)*MAPPING_FACTOR);

typedef struct // ItemRecord struct
{
  BCD upc[BCD_KEY_SIZE];
  Radix40 description[DESCRIPTION_WORDS];
  unsigned price;
} ItemRecord;

typedef struct // PriceFile struct
{
  FILE *dos_file_stream;
  ItemRecord **item_cache;
  unsigned *file_record_number;
} PriceFile;

const int QUESTIONABLE = 0;
const int FOUND = 1;
const int NOT_IN_FILE = 2;
const int FILE_FULL = 3;

const int INPUT_MODE = 0;
const int LOOKUP_MODE = 1;

const int CLEAR_FILE = 0;
const int KEEP_FILE = 1;

unsigned compute_hash(char *key_value);

unsigned compute_file_hash(char *key_value);

unsigned compute_cache_hash(char *key_value);

int lookup_record(PriceFile* price_file, char *ascii_key_value, 
ItemRecord **item_record);

int lookup_record_number(PriceFile* price_file, char *ascii_key_value, 
unsigned *record_number);

int write_record(PriceFile* price_file, ItemRecord new_record);

unsigned compute_starting_cache_hash(unsigned cache_index);

unsigned compute_ending_cache_hash(unsigned cache_index);

PriceFile* initialize_price_file(char *price_file_name, int file_mode);

void terminate_price_file(PriceFile* price_file);

void position_record(PriceFile* price_file, unsigned record_number);

int lookup_record_and_number(PriceFile* price_file, char *ascii_key_value,
ItemRecord **item_record, unsigned *record_number);